Sweet potatoes do double duty when mashed into a batter for homemade waffles the morning after Thanksgiving.
Heat a waffle iron according to manufacturer's instructions and coat with nonstick cooking spray.
In a large bowl, combine the flour, baking powder, salt, sugar, ginger, and zest.
In a small bowl, mix together the egg yolks, sweet potato, butter, and milk until thoroughly combined.
Make a well in the center of the dry ingredients, pour in the liquid ingredients and stir to combine. The batter should be thick but pourable.
In a separate bowl, whip the egg whites until stiff and gently fold them into the batter until barely blended; don't worry about a few streaks of white.
Cook the waffles according to the directions on your waffle iron. If you don't have an indicator light, you can tell the waffles are done when they release easily from the iron and are browned and crisp on the outside. Serve immediately.